So some updates:
The frame manufacturer did send me a new swing arm. They shipped it free of charge and it wasn't cheap for them to do so. The new swing arm looks a lot better and the shock mount is tweaked a bit to allow a larger diameter tire.
The new swing arm is on the left.
The dual disc brakes didn't work out. They leaked at the pistons and I'll have to fix them later on. In the meantime I found some Julie Magura ebike brakes. These have the brake cutoff sensors build inline with the hydraulic lines. These work good at slower speeds, but I'll have to depend on regen braking at higher speeds. I still need to wire it up for that.
